Loud speaker drivers include the following components: an electromagnet; a moving voice coil; and a speaker cone attached to the coil. The speaker driver components operate together to generate audible sounds, such as music or voice transmissions. The electromagnet receives sound transmissions in the form of electrical signals from a sound amplifier. The variations in the signal frequency and amplitude causes the magnetic flux of the magnet to change in response thereto. The moving voice coil and the speaker cone, responsive to the changes in magnetic flux, move in a manner characteristic of the frequency and amplitude of the signal.
The speaker cone is the actual component which is responsible for converting the electrical signals into audible sound. The movement of the speaker cone displaces the air in the vicinity of the speaker cone. The displaced air creates sound waves having an amplitude and frequency indicative of those from the electrical signal, and in this manner, the desired audible sound reproduction is achieved.
The loud speaker drivers are typically enclosed in a sturdy, non-vibrational housing. The electromagnet and voice coil are recessed into the housing and the face of the speaker cone is generally focused outward from the housing to direct the audible sound outward into the listening area. A perforated grill made of a rigid material, such as plastic or metal, or an acoustically transparent foam is placed over the exposed surface of the speaker cone to protect it.
It is known in the audio reproduction art that the transmissions of vibrations to the body intensifies the enjoyment of listening to music. For example, in U.S. Pat. Nos. 4,064,376 and 4,354,067 two devices for the implantation of an vibration device within a the seat and backrest respectively of a chair are disclosed. The audio sensation created by the vibrations transmitted through the body cavity of the person sitting in the chair intensifies the enjoyment of the music. In U.S. Pat. No. 4,757,548, a speaker which transmits sonic vibrations to liquid and solid media is disclosed. U.S. Pat. No. 4,778,027 teaches the placement of speakers faced toward a surface to be vibrated. During operation, the sonic energy generated by the speaker is transmitted to the surface causing it to vibrate.
It is also known in the audio reproduction art to use sound induced vibrations to aid the hearing impaired. In U.S. Pat. Nos. 3,423,544 and 2,858,376 respectively, two electro-acoustic bone conduction receivers mounted onto the elongated portion of eye glasses are disclosed. The bone conduction receiver as described in both of these references is an electro-mechanical device which transforms electric currents into mechanical vibrations and transmits the latter to the bones of the skull of the wearer of the glasses in the vicinity of the ear. This process of transmitting sounds to the inner ear of a deaf person is known to give good results in many instances where the inner ear is in reasonably good condition, although the middle ear may be seriously defective.
In U.S. Pat. No. 4,961,227, a loud speaker system includes a speaker cone, a propagation member and a vibrational housing which encloses the speaker cone and the propagation member. The vibrations on the speaker cone are transmitted to the vibrational housing through the propagation member.
In some settings, it is desirable that the vibrations from a loud speaker be directly felt by a human body in more accurate and focused fashion. For example, the human body's feeling of the vibrations generated by music can be used to convey rhythm, timing and steps to the deaf. In another example, when a person listens a music, the body feeling towards vibrations of the loud speaker enables the person to sense how hard and how quick the player strikes the keys of a piano. In some other settings, in addition to the requirements of more accurate and focused vibration transmission, it is also desirable to transmit the vibrations from the loud speaker to the human body without transmitting audible sounds from the loud speaker. For example, loud speakers can be installed in a chair so a person sitting in the chair can feel the vibrations without disturbing others.